Once you have designed the panel, you can exit design mode and switch to display mode by clicking on the button  in the toolbar or selecting “Stop design mode” in the context menu.

If you want to switch from display mode back to design mode, right-click on the panel and choose “Design mode” in the context menu or press the key combination <Ctrl>+<D>.

Every QPanel display can only be changed to design mode individually. Then the toolbox appears for all panels in design mode. Other panels can still be in display mode.

The panel mode can be identified by the upper toolbar which is only displayed in design mode.